1 /*-
2 * SPDX-License-Identifier: BSD-2-Clause
3 *
4 * Copyright (c) 2003 Marcel Moolenaar
5 * All rights reserved.
6 *
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
9 * are met:
10 *
11 * 1. Redistributions of source code must retain the above copyright
12 * notice, this list of conditions and the following disclaimer.
13 * 2. Redistributions in binary form must reproduce the above copyright
14 * notice, this list of conditions and the following disclaimer in the
15 * documentation and/or other materials provided with the distribution.
16 *
17 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
18 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
19 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
20 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
21 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
22 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
23 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
24 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
25 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
26 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
27 */
28
29 #include <sys/types.h>
30 #include <sys/ucontext.h>
31 #include <signal.h>
32 #include <stdlib.h>
33 #include <strings.h>
34
35 typedef void (*handler_t)(uint64_t, uint64_t, uint64_t);
36
37 /* Prototypes */
38 static void sigctx_wrapper(ucontext_t *ucp, handler_t func, uint64_t *args);
39
40 __weak_reference(__signalcontext, signalcontext);
41
42 int
__signalcontext(ucontext_t * ucp,int sig,__sighandler_t * func)43 __signalcontext(ucontext_t *ucp, int sig, __sighandler_t *func)
44 {
45 uint64_t *args;
46 siginfo_t *sig_si;
47 ucontext_t *sig_uc;
48 uint64_t sp;
49
50 /* Bail out if we don't have a valid ucontext pointer. */
51 if (ucp == NULL)
52 abort();
53
54 /*
55 * Build a signal frame and copy the arguments of signal handler
56 * 'func' onto the stack and do the funky stack alignment.
57 * This means that we need an 8-byte-odd alignment since the ABI expects
58 * the return address to be pushed, thus breaking the 16 byte alignment.
59 */
60 sp = (ucp->uc_mcontext.mc_rsp - 128 - sizeof(ucontext_t)) & ~15UL;
61 sig_uc = (ucontext_t *)sp;
62 bcopy(ucp, sig_uc, sizeof(*sig_uc));
63 sp = (sp - sizeof(siginfo_t)) & ~15UL;
64 sig_si = (siginfo_t *)sp;
65 bzero(sig_si, sizeof(*sig_si));
66 sig_si->si_signo = sig;
67 sp -= 3 * sizeof(uint64_t);
68 args = (uint64_t *)sp;
69 args[0] = sig;
70 args[1] = (intptr_t)sig_si;
71 args[2] = (intptr_t)sig_uc;
72 sp -= 16;
73
74 /*
75 * Setup the ucontext of the signal handler.
76 */
77 bzero(&ucp->uc_mcontext, sizeof(ucp->uc_mcontext));
78 ucp->uc_mcontext.mc_fpformat = _MC_FPFMT_NODEV;
79 ucp->uc_mcontext.mc_ownedfp = _MC_FPOWNED_NONE;
80 ucp->uc_link = sig_uc;
81 sigdelset(&ucp->uc_sigmask, sig);
82
83 ucp->uc_mcontext.mc_len = sizeof(mcontext_t);
84 ucp->uc_mcontext.mc_rdi = (register_t)ucp;
85 ucp->uc_mcontext.mc_rsi = (register_t)func;
86 ucp->uc_mcontext.mc_rdx = (register_t)args;
87 ucp->uc_mcontext.mc_rbp = (register_t)sp;
88 ucp->uc_mcontext.mc_rbx = (register_t)sp;
89 ucp->uc_mcontext.mc_rsp = (register_t)sp;
90 ucp->uc_mcontext.mc_rip = (register_t)sigctx_wrapper;
91 return (0);
92 }
93
94 static void
sigctx_wrapper(ucontext_t * ucp,handler_t func,uint64_t * args)95 sigctx_wrapper(ucontext_t *ucp, handler_t func, uint64_t *args)
96 {
97
98 (*func)(args[0], args[1], args[2]);
99 if (ucp->uc_link == NULL)
100 exit(0);
101 setcontext((const ucontext_t *)ucp->uc_link);
102 /* should never get here */
103 abort();
104 /* NOTREACHED */
105 }
106